Zootaxa 3693 (4): 479–490 ISSN 1175-5326 (print edition) www.mapress.com/zootaxa/ Article ZOOTAXA Copyright © 2013 Magnolia Press ISSN 1175-5334 (online edition) http://dx.doi.org/10.11646/zootaxa.3693.4.4 http://zoobank.org/urn:lsid:zoobank.org:pub:13EA08B0-9D7C-4845-854C-FECC3C9580F1 A new ectoparasitic distichodontid of the genus Eugnathichthys (Characiformes: Citharinoidei) from the Congo basin of central Africa, with a molecular phylogeny for the genus MELANIE L.J. STIASSNY1 JOHN S.S. DENTON1,2 & RAOUL J.C. MONSEMBULA IYABA3 1American Museum of Natural History, Department of Ichthyology, Central Park West at 79th Street, New York, New York 10024. E-mail:
[email protected] 2Richard Gilder Graduate School, American Museum of Natural History, Central Park West at 79th Street, New York, New York 10024. E-mail:
[email protected] 3Faculté des Sciences, Département de Biologie, Université de Kinshasa B.P 190 Kin XI, Democratic Republic of Congo. E-mail:
[email protected] Abstract A new species of ectoparasitic distichodontid, Eugnathichthys virgatus, is described from localities in the central and western Congo basin. The new species is a fin-eater even at small sizes and, in common with congeners, is capable of biting off sections of heavily ossified fin-rays of large prey species. Prior to the present study, two species were included in this distinctive distichodontid genus: the type species, Eugnathichthys eetveldii, and a second species, E. macroterole- pis, both of which are widely distributed throughout much of the Congo basin. Morphologically, E. virgatus is readily dis- tinguished from its two congeners based on a combination of meristic and morphometric attributes.